[grace-puzzl]

they could be optimizing for how YC posts "new roles", essentially if they deleted their job posts and created a brand new one, YC would register it as a "new" post, so to answer your Q, they totally could be monopolizing it.

[gmjosack]

I'm not familiar with the mechanism in which these posts occur. I'd expect if it were automated I'd notice them more often but I feel like I only have memories of Jerry posts and it feels like it's very often. May be confirmation bias but there's not exactly a way to search for these kinds of posts.